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Moltron1's avatar
Moltron1
Level 5
15 years ago
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SAN Transport AVVI poor performance - tons of "Map Disk Region"

I am having some slow performance when using the SAN transport method of backing up my VMs.  Only getting up to 1,000MB per minute.  Over the network I can get 2,000+.  When I kick off a backup in the VMware client I am getting a ton of "Map Disk Region" tasks kicked off, I'm talking hundreds.  Does this indecate a problem?  Why are there so many? I read somewhere else that this could mean there is fragmentation somewhere, but how do I defrag VMFS?  There does not seem to be a way to do it.  Anyone else seeing this happening?

I'm not sure where to troubleshoot either... I checked on my brocade switch ports and though there were errors, I cleared the counters and re-ran a backup.  Did not receive any errors on the switches.  EMC power path monitor reports between 500 and 1000 IO p/s on the path during the backup.  That seems ok to me for a single server i guess...

2010
Agent for VMware Virtual Infrastructure
Backup and Recovery
Backup Exec

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  • Simon_B_'s avatar
    Simon_B_
    Level 6
    15 years ago

    It could also occur multiple times when changed block tracking is enabled for this particular virtual machine. This for example is the case when you perform incremental/differential VM backups.

    Does the job have this poor error rate throughout the backup or is it only the average rate shown for the job after the job completes? If so: check the rate during the first few minutes of the backup. You also want to check the hard disk waiting queues if you are performing backup to disk or to a deduplication folder

  • Moltron1's avatar
    Moltron1
    Level 5
    15 years ago

    I noticed that on my machines that I was testing with, I did have snapshots and they were pretty old.  They took a while to delete, but once they did WOW what an improvement.  Only about 10 map disk region tasks vs. the hundreds of them before...

    Best of all the job rate started at 2,000 MB/min instead of 100 MB/min.  The job rate after the job completed was 3,755 MB/min.  The job finished in less than half the time as before. 

    Thanks!